JPH0729273A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To enable a stable tape running state by varying a tape running system and setting a maximum oblique condition of a tape guidance guide different from each other according to the running system. CONSTITUTION:When a standard mode is selected, a rotary SW 7 is rotated to a contact A clockwise, and a loading motor 1 is stopped by judging the detection output of the SW 7. Although a cam gear 4 is rotated clockwise by the rotation of the motor 1, no lever 28 is turned. By a pole catcher 29, the movement of a leading guide block 15 is prevented. That is, the block 15 is abutted on and held by the catcher 29, and the tape loading is ended. Then, when a long time mode is selected, the SW 7 is rotated to the contact B by exceeding the contact A, and the motor 1 is stopped. That is, the gear 4 is rotated further clockwise, and a following pin 31 is follow-up moved in a cam groove 5, and the lever 28 is turnd around a shaft 30, and the catcher 29 is removed from a guide groove 24. The block 15 is slidden in the guide groove 24 and abutted on the pole catcher 26. Thus, a tape lower end is stretched strong, and the head touch of an inlet side is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a rotary head digital audio tape recorder (R) which uses a tape cassette having a different number of rotations of a cylinder between a standard mode and a long time mode, or a tape cassette having a different tape thickness.
-DAT), or a tape loading device in a magnetic recording / reproducing device such as a digital video tape recorder (D-VTR).

[0002]

2. Description of the Related Art R-DAT has four types of recording / reproducing modes and two types of reproducing only modes in order to support various digital sources. Although the standard rotation speed of the cylinder is 2000 rpm, in contrast to this, there is also provided a long time mode in which recording / reproduction is performed at a cylinder rotation speed of 1000 rpm and a tape feeding speed of 1/2 of the standard. Therefore, 1
Recording and reproduction must be performed in a state where the cylinder rotation speed is different in one tape running system.

On the other hand, there are two types of consumer digital VTR formats, SD (NTSC specification) and HD (high definition specification). The relationship between the cylinder rotational speed and the head number of both specifications is SD: 2 ch / 4500 rpm, HD. : 2
ch / 9000 rpm or 4 ch / 4500 rpm.

Considering SD and HD compatible VTRs in this format, it is necessary to consider a good tape running system corresponding to two types of cylinder rotation speeds with one VTR running mechanism.

Further, one of the mechanical characteristics of the magnetic tape is stiffness (tape bending rigidity), but this value becomes smaller as the tape becomes thinner, and this greatly affects the contact state between the tape and the head. In general, the smaller the stiffness, the more difficult it is to secure the contact between the tape and the head.

FIG. 13 shows the relationship of the air film amount with respect to the cylinder rotation speed. The abscissa represents the measuring point (angle) from the tape inlet to the tape outlet with respect to the cylinder, and the ordinate represents the air film amount. There is. As shown in the figure, the air film amount at the cylinder inlet increases as the cylinder rotation speed increases. In other words, the rotational speed of the head and the amount of air film on the inlet side change depending on the number of cylinder rotations, and the contact surface pressure of the head applied to the tape changes, so the head lifting force on the tape changes. As a result, the contact state between the tape and the head and the tape running state change depending on the rotational speed of the cylinder, and the head touch on the entrance side and the recording track linearity change.

Conventionally, in order to obtain a tape tension distribution suitable for the number of cylinder revolutions, the inclination angle of the tape pull-out leading guide is slightly deviated from the design value to ensure the head touch on the entrance side and the linearity of the recording track. It was However, in order to improve the head touch on the cylinder inlet side, the state in which the inclination angle of the guide is slightly shifted is not always the optimum recording track linearity state.

FIG. 14 shows the relationship between the tension distribution and the recording track linearity when the tension distribution of the tape is changed (the guide inclination angle is changed) obtained from the experiment. The horizontal axis is the tension distribution ratio, which utilizes the property that the tape repulsive force when the tape is pushed in the thickness direction depends on the tension value, and measures the tape repulsive force at the top and bottom of the tape to replace it with the distributed load. . The ratio is (bottom edge of tape / top edge of tape), and if it is greater than 1, it is underlaying, and if it is less than 1, it is overlaying.

From the figure, it can be seen that there is a tension distribution ratio with which optimum recording track linearity is obtained.
In addition, the tension distribution that provides the optimum recording track linearity varies depending on the tension value, and the tendency of underlining must be increased as the tension value increases.

FIG. 15 shows the relationship between the envelope and the stiffness in a magnetic recording / reproducing apparatus in which the tape running system is adjusted with reference to a standard stiffness tape.
From the figure, it is understood that the envelope is rapidly deteriorated at a certain point as the stiffness decreases.

The contact state between the tape and the head at this time is shown in FIG.
6 (a) and (b). FIG. 7A is a cross-sectional view when the output is obtained with a standard stiffness tape, and FIG. 7B is a cross-sectional view when the stiffness is small and the output is reduced. For standard stiffness tape,
The tape T and the head H are in contact with each other without any gap, and the envelope has no problem and the output does not decrease. When the stiffness becomes smaller, the tape T is lifted from the head H at the central portion C of the head gap, which becomes a spacing loss and causes a reduction in output.

As a remedy for this, in order to obtain an envelope output with a tape having a small stiffness, the tape drive guide system is adjusted to a tape running system suitable for a tape having a small stiffness, by slightly shifting the inclination angle of the tape pull-out guide. The head touch can be improved.

[0013]

In the R-DAT, the standard mode and the long time mode in which the number of rotations of the cylinder is different are recorded and reproduced in the same tape running system, so that only one inclination angle of the leading guide can be set. Therefore, in the present situation, the tape tension distribution suitable for two cylinder rotation speeds is not obtained in each mode. That is, either the standard mode is set to an optimum value to sacrifice the long-time mode, or the mode is compromised.

On the other hand, when the tape running system is adjusted on the basis of the tape having a small stiffness, the relationship between the tape T having the standard stiffness and the head H rises at both ends of the head as shown in FIG. 17, and conversely the tape having the standard stiffness is used. Causes the envelope output to drop.

In a conventional magnetic recording / reproducing apparatus using a magnetic tape such as a VTR, the tape is improved and thinned as the recording time becomes longer, and several kinds of tapes having different thicknesses are used for the apparatus. Has been done. VHS and 8mm VT
In R, tapes with different tape thicknesses and magnetic layers, that is, tapes with different stiffness are recorded and reproduced in the same tape running system, so only one inclination angle of the tape pull-out guide can be set, and the tension distribution suitable for each tape can be set. Is not given. Therefore, neither tape running condition nor head touch has been obtained for both tapes.

In recent years, since the recording capacity is inevitably increased with the digitization of signals, there is a tendency toward a wider band and a narrower track.
Stabilization of head touch is becoming a more important technology.
For this reason, digital VTR standard mode and long-time mode specifications, or digital and NTS with the same tape width are used.
In the C-compatible VTR specification, since the cylinder rotation speed is different for the same tape width, or the tape stiffness is different, it is possible to improve the head touch on the cylinder entrance side and the recording track linearity with high accuracy.
More difficult than VTR, 8mm VTR, or R-DAT.

In order to solve this problem, it is necessary to ensure a stable tape running state by providing one tape running system with an optimum guide tilt angle corresponding to each cylinder rotation speed.

Further, from the two data shown in FIGS. 13 and 14, the tape is run at two kinds of rotation speeds for one VTR running mechanism like the SD and HD compatible consumer digital VTRs. In order to obtain good head touch and recording track linearity under the condition that it is necessary, it is necessary to set the magnitude of the tension value that matches the inclination angle (tension distribution) of the tape guide where the head touch can be obtained.

[0019]

In a magnetic recording / reproducing apparatus having a two-mode cylinder rotation speed, a determination means for determining the rotation speed of the cylinder, a leading guide means for drawing a tape from a cassette and winding the tape around the cylinder at a predetermined angle, The guide means is selectively configured to hold the leading guide means at the first or second position according to the determination result of the determination means.

Further, the leading guide holding means is provided with a first pole catcher capable of projecting and retracting in the movement path of the leading guide means, and a second pole catcher fixed at the second position, and at the same time, the first position. Then, the leading guide means should be tilted slightly.

Further, a tension setting means for variably setting the reel base back tension value according to the cylinder rotation speed is provided.

On the other hand, when cassettes of different tape types (thicknesses) are mounted, the leading guide means is selectively held at the first or second position by the discriminating means for discriminating the tape thickness, depending on the tape type. Secure the tape running system.

[0023]

With the above construction, in the standard mode, the first pole catcher is located at the first position within the moving passage of the tape pull-out leading guide, and the leading guide is held in the first position with a slight inclination. Therefore, the head touch to the tape wound around the cylinder and the linearity of the recording track are secured. Further, in the long time mode, the first pole catcher is retracted from the moving passage, so that the leading guide is reliably held by the second pole catcher arranged at the second position, and stable tape running can be obtained. .

Further, the back tension of the supply-side reel stand is set to an optimum value in accordance with the cylinder rotation speed, and a stable tape tension value is secured.

On the other hand, when a cassette having a standard tape thickness is mounted, the tape thickness discriminating means holds the leading guide means for pulling out the tape and holding it at a slight inclination to the first position to form a predetermined tape running system. When a thin tape cassette is mounted, the tape thickness determining means pulls out the tape by the leading guide means and holds the tape at the second position to form a predetermined tape running system.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a concrete first embodiment of the present invention, a case of two modes, a standard mode (cylinder rotation speed 2000 rpm) and a long time mode (cylinder rotation speed 1000 rpm), will be described below with reference to the drawings. . 1 is a plan view of a tape loading completion state in a standard mode (first position), FIG. 2 is a plan view of a tape loading completion state in a long time mode (second position), and FIG. 3 is a cylinder inlet at a first position. FIG. 4 is a side view of the side leading guide, FIG. 4 is a side view of the cylinder inlet side leading guide in the second position, and FIG. 5 is a side view of the cylinder outlet side leading guide in the first position.

In the figure, 1 is a loading motor having a driving gear 2, 3 is an idle gear, 4 is a front cam gear having a cam groove 5, 6 is a rotation angle detecting gear in which a rotary SW 7 is coaxially formed integrally. 8, 9 and 10 are idle gears for transmitting driving force, 11 and 12 are driven gears which mesh with the idle gear 10 and rotate in the same direction, and the driven gears 11 and 12 are provided with drive levers 13 and 14, respectively. Coaxially coupled. 15 and 16 are links 17 and 1, respectively
8 is a leading guide block for pulling out a tape, which is connected to drive levers 13 and 14 via 8. The leading guide blocks 15 and 16 have vertical guide rollers 19 and
20 and the inclined guide poles 21 and 22 are attached.

Reference numeral 23 is a cylinder, 24 and 25 are guide grooves formed in a chassis (not shown), 26 is a second pole catcher provided on the chassis, 27 is a pole catcher on the tape outlet side, and 28 is a tape catcher. A first pole catcher 29 is attached to one end of the lever and is a lever that rotates around a shaft 30 on the chassis. A follow-up pin 31 that engages with the cam groove 5 is attached to the other end of the lever 28.

A feature of the present invention is that the leading guide block 1 is provided on the tape inlet side of the cylinder 23 when the tape is completely pulled out.
First and second pole catchers 29, 26 for selectively holding the 5 in the two positions are arranged so that the first pole catcher 29 holds the leading guide block 15 in the standard mode. Further, in the long time mode, the first pole catcher 29 retracts from the guide groove 24, the leading guide block 15 is positioned and held by the second pole catcher 26 arranged at the second position, and the tape is wound around the cylinder 23. This is the point of configuration.

The operation of the present invention having the above configuration will be described. First, the leading guide block 1 for pulling out the tape
The drive mechanisms 5 and 16 will be described. The rotational driving force of the loading motor 1 is from the drive gear 2, the idle gear 3, the front cam gear 4, the rotation angle detecting gear 6, the idle gears 8, 9,
It is transmitted to the driven gears 11 and 12 via 10. When the driven gears 11 and 12 rotate in the clockwise direction (CW), the levers 13 and 14 rotate to CW, respectively, so that the leading guide blocks 15 and 16 can guide the tape while pulling out the tape via the links 17 and 18. The tape is wound around the cylinder 23 by sliding along the grooves 24 and 25.

When the standard mode is selected, the rotary SW 7 rotates to the CW up to the contact A in FIG. 1, the determination is made by the detection output of the rotary SW 7, and the loading motor 1 is stopped. The front cam gear 4 rotates to CCW by the rotation of the loading motor 1, but the lever 28 does not rotate because the follower pin 31 follows the concentric circle of the cam groove 5. Therefore, the first pole catcher 29 is located at a predetermined position of the guide groove 24 and prevents the leading guide block 15 from moving. That is, the leading guide block 15 is held in contact with the first pole catcher 29, and the tape loading is completed (see FIG. 1).

Next, when the long time mode is selected, the rotary SW 7 rotates beyond the contact A to the contact B to stop the loading motor 1 as shown in FIG.
That is, since the front cam gear 4 further rotates to CCW, the follower pin 31 follows the cam groove 5 and moves the lever 28 to the shaft 3.
Rotate to CCW centered on 0 to move the first pole catcher 2
9 is removed from the guide groove 24. Therefore, the leading guide block 15 slides in the guide groove 24 and is held in contact with the second pole catcher 26.

Since the air film amount on the tape outlet side is not easily influenced by the number of rotations of the cylinder 23, in FIG.
The position of the pole catcher 27 with respect to the leading guide block 16 on the tape outlet side is set to the same position as the position in the standard mode of FIG. 1, but like the tape inlet side, the movable first pole catcher 29 and It may be configured with the fixed second pole catcher 26.

Here, the first pole catcher 2 on the entrance side
9 and the shapes of the second pole catcher 26 will be described. The larger the rotation speed of the cylinder 23, the larger the air film amount on the inlet side. Therefore, in the standard mode in which the number of rotations is high, the vertical guide roller 19 of the leading guide block 15 is pressed against the first pole catcher 29 at an angle of θ ° so as to press the pole as shown in FIG. The contacted surface 29a of the catcher 29 is formed by cutting by θ °.

By forming in this way, the tape lower end edge side is strongly stretched, so that the amount of air film in the vicinity of the head side head scanning line is reduced and the head touch on the entrance side is improved. However, when the tape is laid underneath, a force acts on the tape in a direction to move away from the lead surface of the cylinder. In the configuration of the present invention, the vertical guide roller 19 is slightly lowered by inclining the leading guide block 15 by the angle θ ° with the first pole catcher 29 as the rotation support shaft, and the linearity of the recording track with respect to the tape. Has been secured. The pressure contact shape of the cylinder outlet side with respect to the pole catcher 27 is formed in such a shape that it is inclined in the direction opposite to the cylinder inlet side and the tape upper edge side is strongly stretched (see FIG. 5).

Second pole catcher 2 in long time mode
As shown in FIG. 4, the leading guide block 15 is pressed against 6 so as to be substantially parallel to the reference plane.
The vertical guide roller 19 and the inclined guide pole 21 are formed so as to reduce the amount of underlayment and descending of the tape on the entrance side when the tape loading is completed.

Next, the loading operation of the present invention will be described with reference to the flowchart of the loading mechanism shown in FIG. When a cassette (not shown) is attached to the cassette holder (not shown) (step 41), an identification hole (not shown) provided on the back surface of the cassette and a mode detection SW (see figure) provided on the mechanism. (Not shown), it is determined that the L level of the detection output is the standard mode and the H level of the detection output is the long time mode (step 42).

When the standard mode is determined, the rotary S
A driving voltage is applied to the loading motor 1 until the detection output of the contact A of W7 becomes H level (step 43), and the leading guide blocks 15 and 16 are moved (step 4).
4) Pull the tape out of the cassette. When the leading guide blocks 15 and 16 are crimped to the first pole catchers 29 and 27 (step 45), the detection output of the contact A becomes H level (step 46), the loading motor 1 is stopped (step 52), and loading is performed. Complete.

In the long time mode, the drive voltage is applied to the loading motor 1 until the detection output of the contact B of the rotary SW 7 becomes H level (step 47). The leading guide blocks 15 and 16 move along the guide grooves 24 and 25 (step 48), and the leading guide block 1 on the inlet side is moved.
5 contacts the first pole catcher 29 once, but since the front cam gear 4 rotates further, the follower pin 31 moves along the cam curve of the cam groove 5. Therefore, the first pole catcher 29 separates from the guide groove 24 (step 49).

As a result, the leading guide block 15 further moves and is pressed against the second pole catcher 26 (step 50). At that time, the detection output of the contact B becomes H level (step 51), the loading motor 1 is stopped (step 52), and the loading is completed. The leading guide block 16 on the exit side is the first pole catcher 2
The driven gear 12 may be formed as a missing gear so as not to move after it comes into contact with 7. Alternatively, similarly to the leading guide block 15 on the inlet side, the second pole catcher may be provided on the cylinder outlet side.

Next, as a second embodiment of the present invention, a specific structure for obtaining an optimum tape running system when using two or more types of tape cassettes having different stiffnesses will be described. Here, considering the case of using a standard tape cassette and a thin tape cassette, that is, a tape cassette having a small stiffness, it is possible to substitute the standard tape cassette for the standard mode and the thin tape cassette for the long time mode. it can.

The configuration and operation in this case are exactly the same as in the standard mode and the long time mode described above. That is, when the cassette is mounted on the cassette holder, the L level is determined to be the standard tape mode and the H level is determined to be the thin tape mode from the output of the mode detection switch attached to the identification hole provided on the back surface of the cassette and the mechanism. After discrimination
A drive voltage is applied to the loading motor 1 to move the leading guide blocks 15 and 16 and wind the tape around the cylinder 23. After that, it operates according to the flowchart shown in FIG. 7 as described above. In step 42 ′ of FIG. 7,
Instead of the "standard / long-time mode discrimination" in step 42 of FIG. 6, "standard / thin tape mode discrimination" is performed. With the above configuration, it is possible to set the optimum inclination of the guide according to the tape thickness when the tape loading is completed, that is, the stiffness. Other than that, since it is the same as FIG. 6,
The description of the operation is omitted.

Next, as a third embodiment of the present invention, a tape width of 6.35 mm and a cylinder rotation speed of 4500 rpm (SD
The case of two modes of mode; NTSC specification) and 9000 rpm (HD mode; high-definition specification) will be described. In this case as well, the structure and operation of the mechanism are the same as those in the first embodiment described above. The HD mode corresponds to the loading completion state at the first position in FIG. 1, and the SD mode corresponds to the second position in FIG. The loading completion status corresponds. That is, it is possible to substitute the SD mode for the standard mode and the HD mode for the long time mode.

The difference from the first and second embodiments is that HD
In order to obtain the optimum tape tension value for each mode of SD mode and SD mode, it is the point to set the reel base back tension value according to each mode. Since it is exactly the same as that of 4, the description and operation of each will be omitted.

Next, a tension value control method for obtaining the optimum track linearity in a favorable head touch state will be described. Normally, the tension value is controlled to be constant by controlling the rotation of the reel stand. That is,
The change in the distance between the magnet arranged on the tension arm and the magnetic sensor (for example, a hall element) arranged on the chassis is taken out as the output of the magnetic sensor, and the output of this is used to control the drive of the reel stand. This method is well known and will not be described in detail.

FIG. 8 is a block diagram of the tension control circuit. The magnetic sensor (not shown) outputs a detection signal according to the position of the tension arm (not shown), that is, according to the tension value. The detection signal is compared with each reference voltage corresponding to the cylinder rotation speed in the comparison circuit 61. This comparison output is input to a voltage generation circuit 62 that generates two types of voltages corresponding to the SD mode and the HD mode by resistance voltage division, and the SD mode voltage and the HD mode voltage are output. These voltages are output from the microcomputer 63 via the selector 64 according to the cylinder speed.
The control voltage selected by the control signal from is applied to the reel motor to control the drive of the reel stand. As a result, the tape tension value is controlled to a value predetermined by the cylinder rotation speed.

In the embodiment of the present invention, when comparing the SD mode and the HD mode, the HD mode has a larger underlay. From FIG. 14, in order to obtain the optimum recording track linearity in the HD mode in which the degree of underlayment is larger than that in the SD mode, it is necessary to make the tension value in the HD mode larger than that in the SD mode. In other words, head touch and recording track linearity are required. In order to obtain the following, the degree of underlayment and the tension value tend to increase as the cylinder rotation speed increases.

Next, a series of operations will be described with reference to FIG. First, the SD mode or the HD mode is discriminated from the number of rotations of the cylinder (step 65). When the HD mode is determined, the drive voltage is applied to the loading motor 1 until the detection output of the contact A of the rotary switch 7 becomes H level (step 66), and the leading guide block 15,
16 is moved (step 67), and the tape is pulled out from the cassette. The leading guide blocks 15 and 16 are crimped to the first pole catchers 29 and 27 (step 68).
Then, the detection output of contact A becomes H level (step 6
9), the loading motor 1 stops (step 70)
Loading is complete. At that time, the tension control selects the output of the voltage generation circuit 62 by the control signal from the microcomputer 63 based on the determination result of the rotation speed of the cylinder,
A DC control voltage for reel base drive control is output (step 71). With this DC control voltage, the reel base is driven and controlled, and the tape tension value is controlled to be constant (step 72). By this series of operations, the back tension value of the supply side reel stand suitable for the degree of underlaying set to obtain a good head touch in the HD mode is set.

If the SD mode is determined, the drive voltage is applied to the loading motor 1 until the detection output at the contact B of the rotary switch 7 becomes H level (step 6).
6) The leading guide blocks 15 and 16 are moved (step 67), and the tape is pulled out from the cassette. The leading guide block 15 on the inlet side once contacts the first pole catcher 29, but the follower pin 31 moves along the cam curve of the cam groove 5 because the front cam gear 4 further rotates. Therefore, the first pole catcher 29 has the guide groove 24.
(Step 73).

As a result, the leading guide block 15 further moves and is pressed against the second pole catcher 26 (step 74). At that time, the detection output of the contact B becomes H level (step 75), the loading motor 1 is stopped (step 76), and the tape loading is completed. Note that the leading guide block 16 on the outlet side does not move further after coming into contact with the first pole catcher 27.
Is formed in the shape of a missing gear. At that time, the tension control is performed by the microcomputer 6 based on the determination result of the rotation speed of the cylinder.
The output of the voltage generation circuit 62 is selected according to the control signal from No. 3, and the DC control voltage for reel base drive control is output (step 77). With this DC control voltage, the reel base is driven and controlled to keep the tape tension value constant (step 78). By this series of operations, the back tension value of the supply side reel base 81 suitable for the degree of underlaying set to obtain a good head touch in the SD mode is secured.

A method of controlling the tension value different from the above will be described with reference to the drawings. 10 is a plan view of the main part in the SD mode, and FIG. 11 is a plan view of the main part in the HD mode. First, in the SD mode of FIG. 10, that is, when the tension is low, it is determined by the frictional force of the band brake 83 wound around the supply-side reel base 81. One end of the band brake 83 is attached to the tension lever 84, and the other end is attached to a chassis (not shown). Reference numeral 85 is a slide lever that slides according to the SD / HD mode, one end of which is a rotatable hook lever 8
The spring 87 is suspended between the hook lever 86 and the tension lever 84 by engaging with the pin 86a of No. 6 and biases the tension lever 84 to CCW. The tape T is supplied from the supply side reel 88 to the tension post 84a vertical guide 89,
It is wound around the cylinder 23 via 90, 19 (tilt posts are not shown). Reference numeral 82 is a take-up reel stand.

When the tension is low in FIG. 10, the band brake 83 is wound around the reel base 81 relatively loosely, and a slight braking force is applied to the reel base 81 to give an appropriate tape tension value. Next, when the HD mode is entered, the slide lever 85 slides in the direction of arrow C, resulting in the state shown in FIG. That is, the hook lever 86 rotates to CW to extend the spring 87, and the tension lever 84 rotates to CCW. As a result, the braking force applied to the reel base 81 by the band brake 83 increases. That is, the back tension of the reel base 81 increases, and the tension value of the tape T fed from the supply-side reel 88 increases.

A series of operations when this tension control mechanism is adopted will be described with reference to the flowchart of FIG. Since the process is the same as in FIG. 9 up to the middle, the same numbers are assigned and the description thereof is omitted. In HD mode,
The rotation of the loading motor 1 completes the tape loading (step 70). At that time, the tension control is the determination result of the rotation speed of the cylinder 23 (step 65).
Based on the above, the slide lever 85 is slid (step 91), and the band brake 8 for the supply side reel base 81 is moved.
Increase the braking force of 3. As a result, the supply side reel base 81
Since the back tension value of the tape is increased, the tension value when the tape is pulled out is increased (step 92). With this series of operations, the tension value suitable for the degree of underlaying set in order to obtain a good head touch in the HD mode is secured.

In the SD mode, the above is the same until the tape loading is completed (step 76), and the tension control at that time is at the position where the slide lever 85 slides to the right side shown in FIG. 11 (step 93). The braking force of the band brake 83 on the supply-side reel base 81 is small (step 94). With this series of operations, SD
A tension value suitable for the degree of subbing set in order to obtain a good head touch in the mode is secured.

[0055]

With the above construction, the tape traveling system is made variable, and the optimum inclination state of the tape guide guide can be set depending on the traveling system. Therefore, even if the cylinder rotational speed changes, Even if the thickness of the tape, that is, the stiffness changes, the inclination angle of the tape guide can be set according to the change, and highly accurate linearity and stable head touch can be obtained. In particular, this is effective when the tape must be run at two cylinder rotation speeds by one mechanism like a compatible digital VTR of SD mode and HD mode.

[Brief description of drawings]

FIG. 1 is a plan view when tape loading is completed in a standard mode.

FIG. 2 is a plan view when tape loading is completed in the long time mode.

FIG. 3 is a partial cross-sectional view of one leading guide block at a first position.

FIG. 4 is a partial cross-sectional view of one leading guide block in a second position.

FIG. 5 is a partial cross-sectional view of the other leading guide block at the first position.

FIG. 6 is a flowchart of a tape loading operation.

FIG. 7 is a flowchart of a tape loading operation in a standard / thin tape mode.

FIG. 8 is a block diagram of a tension control circuit.

FIG. 9 is a flowchart of a tape loading operation in SD / HD mode.

FIG. 10 is a plan view of a main part of a mechanism in SD mode.

FIG. 11 is a plan view of a main part of a mechanism in HD mode.

FIG. 12 is a tape loading operation flowchart of another example in the SD / HD mode.

FIG. 13 is a diagram showing a relationship between a cylinder rotation speed and an air film amount.

FIG. 14 is a relationship diagram of a tension distribution ratio and recording track linearity.

FIG. 15 is a relationship diagram between tape stiffness and envelope.

FIG. 16 is a cross-sectional view showing a contact state between the tape and the head.

FIG. 17 is a cross-sectional view showing another contact state between the tape and the head.

[Explanation of symbols]

 15 Leading guide block 23 Cylinder 26 Second pole catcher (holding means) 29 First pole catcher (holding means) 61 Comparison circuit 62 Voltage generation circuit 63 Microcomputer 64 Selector 81 Supply side reel base 83 Band brake 84 Tension lever 85 Slide lever 86 Hook lever 87 spring

Claims (8)

[Claims] 1. A magnetic recording / reproducing apparatus having a two-mode cylinder rotation speed, a determination means for determining the cylinder rotation speed, a leading guide means for drawing a tape from a cassette and winding the tape around the cylinder at a predetermined angle, and the leading guide. Holding means for holding the means in the first or second position. 2. A magnetic recording / reproducing apparatus having a two-mode cylinder rotation speed, a judgment means for judging the cylinder rotation speed, a leading guide means for drawing a tape from a cassette and winding the tape around the cylinder at a predetermined angle, and the leading guide. A magnetic recording / reproducing apparatus comprising: holding means for holding the means at the first or second position; and tension setting means for variably setting a reel base back tension value according to the cylinder rotation speed. 3. A magnetic recording / reproducing apparatus for recording / reproducing by mounting a cassette having tapes having different tape thicknesses, wherein the discriminating means discriminates the tape thickness, and the tape is pulled out from the cassette to a predetermined angle on the cylinder. A magnetic recording / reproducing apparatus, comprising: a leading guide means for winding and a holding means for holding the leading guide means at a first or second position. 4. The holding means for holding at the first position is a first pole catcher which can be retracted into and out of the moving path of the leading guide means, and the means for holding at the second position is a second pole catcher.
4. The magnetic recording / reproducing apparatus according to claim 1, wherein the magnetic recording / reproducing apparatus is a second pole catcher arranged at a position. 5. The magnetic recording / reproducing apparatus according to claim 1, wherein the leading guide means at the first position is slightly inclined. 6. The magnetic recording / reproducing apparatus according to claim 1, wherein the pair of leading guide means at the first position are slightly inclined in mutually opposite directions. 7. The magnetic recording / reproducing apparatus according to claim 2, wherein the tension setting means drives and controls the rotation of the supply side reel base based on a tape tension detection signal. 8. The tension setting means includes a band brake for braking the supply reel base, a tension lever connected to the band brake for detecting tape tension, a coil spring for urging the tension lever, and a coil spring. 3. The magnetic recording / reproducing apparatus according to claim 2, wherein the magnetic recording / reproducing apparatus comprises a sliding or rotating member for varying the force.